2,4-D, (2,4-dichlorophenoxy)acetic acid, is a phenoxyacetic acid herbicide, and its herbicidal activity is described in The Pesticide Manual, Fifteenth Edition, 2009. 2,4-D, which acts as a growth inhibitor, provides post-emergent control of many annual and perennial broadleaf weeds particularly in cereals and turf. 2,4-D has been in wide use since its introduction in the 1940s and certain weeds have developed a tolerance to both it and to other herbicides whose mode of action is that of acting as an auxinic growth inhibitor. Resistance of corn poppy (Papaver rhoeas) to 2,4-D is well documented (Torra et al., 2010. Evaluation of herbicides to manage herbicide-resistant corn poppy (Papaver rhoeas) in winter cereals. Crop Protection. 29, 731-736). It would be desirable to find an effective replacement for 2,4-D for the post-emergent control of phenoxyalkanoic acid herbicide-resistant weeds.